CN105909331B - A kind of electricity generation system of optimization output power regulation - Google Patents

Abstract

A power generation system, including a first power generation cycle, a second power generation cycle, a heating medium pipeline, a cooling medium pipeline and a control device: the first power generation cycle and the second power generation cycle share an evaporator and a condenser, which are respectively set to detect the respective generators The power detector of the generated power, the inlet and outlet of the heating medium of the evaporator are provided with a heating medium supply temperature detector and a heating medium discharge temperature detector; the control device is based on the power detector, temperature detector and the first power generation cycle and the second The working state of the power generation cycle controls at least one of the high-pressure turbine and the medium-pressure turbine in the first power generation cycle to start, and controls the high-pressure turbine to start or shut down in the second power generation cycle.

Description

A power generation system with optimal regulation of output power

technical field

The present invention relates to a power generation system, in particular to a power generation system using an unstable heat source such as ground heat or waste heat as a heat supply source and a control method for the power generation system.

Background technique

With the depletion of fossil energy and the deterioration of the global environment, energy security has attracted more and more attention. The use of energy is related to the economic lifeline and social security of a country, and has long been promoted to the basic development strategy of the country. All countries in the world attach great importance to the effective use of energy. my country's energy utilization rate is only about 33%, which is about 10% lower than that of developed countries .

An important reason for the low energy utilization rate in my country is that energy has not reached cascade utilization, and a large amount of medium and low temperature energy has not been fully utilized. Therefore, improving the utilization of medium and low temperature energy is a key measure to improve energy utilization efficiency. Medium and low temperature heat sources mainly include two parts: the first is the waste heat discharged in industrial production, such as the exhaust and smoke exhaust of various smelting furnaces, heating furnaces, internal combustion engines and boilers in metallurgy, chemical industry, building materials, machinery, electric power and other industries. As my country's industrial energy consumption accounts for about two-thirds of the country's total energy consumption, and more than 50% is discharged in the form of medium and low temperature waste heat, so recycling this part of heat has great potential for energy saving; the second part is solar energy, geothermal energy, etc. Medium and low temperature renewable energy, with the adjustment of my country's energy structure, the proportion of renewable energy will increase. Strengthening the use of these medium and low temperature heat sources will reduce the consumption of fossil energy and achieve the effect of energy saving and emission reduction.

The technology of using medium and low temperature thermal energy to generate electricity is mainly a thermal power generation system based on the Rankine cycle. The dual mass cycle power generation system is a major medium and low temperature thermal power generation system. The feature of dual substance cycle power generation technology is that the hot water does not directly contact the power generation system, and a medium with a low boiling point, such as n-butane, isobutane, ethyl chloride, ammonia and carbon dioxide, is used as the circulating working fluid to convert the hot water The heat is transferred to some kind of low-boiling point medium, and the low-boiling point medium drives the steam turbine to generate electricity.

In duplex cycle power generation, hot water is only used as a heat source and does not directly participate in the thermal cycle itself. First, hot water from a medium and low temperature heat source flows through a surface evaporator. To heat the low boiling point medium in the evaporator. The low-boiling point medium absorbs heat in the evaporator and turns into steam with a certain pressure, which drives the steam turbine and drives the generator to generate electricity. The gas discharged from the steam turbine is condensed into a liquid in the condenser, and the liquid is sent to the heat exchanger by a pump, where it absorbs heat and evaporates into a gas again. In this way, the heat of the hot water is continuously transferred to the low boiling point medium for continuous power generation.

The disadvantage of the power generation system using geothermal or waste heat as the medium and low temperature heat source is the instability of the heat source. Due to the instability of the heat source, it is necessary to make a specific design for the power generation device, such as using multiple power generation cycles, so that it can adapt to large changes. heat source heat. The invention patent of CN102691541B proposes a method that has multiple power generation cycles, and a heating medium cut-off valve and a cooling medium cut-off valve are set on one of the power generation cycles, so that the heat can be properly distributed to multiple power generation cycles according to the change of the heat source. generate electricity.

However, the invention of CN102691541B still has shortcomings. On the one hand, for each power generation cycle, it is necessary to set up specific heating medium and cooling medium input and output pipelines, and at the same time, each power generation cycle also needs to set up an evaporator and a condenser. This leads to an increase in the cost and expense of the power generation system; on the other hand, for a specific power generation cycle, it takes a certain amount of time to start or stop it, and frequent start and stop of the power generation cycle will affect its work efficiency and system performance.

Contents of the invention

The invention provides an optimized power generation system and a control method thereof, which can reduce the switching frequency of a specific power generation cycle in the technical solution of the CN102691541B invention in the case of heat source fluctuations, thereby improving system performance.

A power generation system, comprising a first power generation cycle, a second power generation cycle, a heating medium pipeline, a cooling medium pipeline, and a control device; the control device is used to: Controlling the operation of the first power generation cycle and the second power generation cycle is characterized in that: the first power generation cycle and the second power generation cycle share the evaporator and the condenser; the heating medium enters the evaporator through the heating medium pipeline to heat the working medium , discharged from the evaporator; the cooling medium is discharged from the condenser after condensing the exhaust gas of the first power generation cycle and the second power generation cycle through the cooling medium pipeline; the working medium outlet of the evaporator is divided into two paths, wherein One path flows to the first power generation cycle through the first channel, and the control device controls whether the other path flows to the second power generation cycle through the second channel through a flow valve, thereby controlling whether to start the second power generation cycle.

Preferably, the first power generation cycle is a main power generation system, which has a high-pressure turbine and a medium-pressure turbine; the second power generation cycle is a slave power generation system, which has a high-pressure turbine; the control device is based on the heating medium and the first power generation cycle and In the working state of the second power generation cycle, at least one of the high-pressure turbine and the medium-pressure turbine in the first power generation cycle is controlled to be started, and the high-pressure turbine of the second power generation cycle is controlled to be started or shut down.

Preferably, the high-pressure turbine and the medium-pressure turbine of the first power generation cycle are coupled to the generator through a rotating shaft, so as to drive the generator to generate electricity.

Preferably, the outlet pipeline of the working medium of the first power generation cycle evaporator is divided into two paths, one of which communicates with the inlet of the working medium of the high-pressure turbine through the first valve, and the other one communicates with the inlet of the medium-pressure turbine through the second valve. The working medium inlet of the turbine is connected; the working medium outlet pipeline of the high-pressure turbine is divided into two paths, one of which is connected to the working medium inlet of the medium-pressure turbine through the third valve, and the other is connected to the condenser through the fourth valve. The inlet is communicated; the outlet of the working medium of the medium-pressure turbine is communicated with the inlet of the condenser.

Preferably, the heating medium inlet pipeline of the second power generation cycle is provided with a heating medium cut-off valve, the cooling medium inlet pipeline is provided with a cooling medium cut-off valve, and the control device is based on the heating medium and the first power generation cycle and the second power generation cycle. The working state controls the opening and closing of the first valve, the second valve, the third valve, the fourth valve, the heating medium shutoff valve and the cooling medium shutoff valve.

Preferably, the first power generation cycle and the second power generation cycle have power detectors to detect the power generation of their respective generators, and the inlet and outlet of the heating medium of the evaporator are provided with a heating medium supply temperature detector and a heating medium discharge temperature Detector.

Preferably, the control device controls the first valve, the second valve, the third valve, the fourth valve and the flow valve according to the power detector, the temperature detector and the working status of the first power generation cycle and the second power generation cycle switch. .

Preferably, when the temperature of the heating medium supplied increases from low to high, the control device sequentially activates the high-pressure turbine of the first power generation cycle, the medium-pressure turbine of the first power generation cycle, and the high-pressure turbine of the second power generation cycle. Turbine.

Preferably, when the temperature of the heating medium supplied is from high to low, the control device sequentially shuts down the medium-pressure turbine of the first power generation cycle and the high-pressure turbine of the second power generation cycle; then, starts the medium-pressure turbine of the first power generation cycle, shuts down High-pressure turbine for the first power generation cycle.

As another aspect of the present invention, the control method of the above-mentioned power generation system is provided, wherein, when the temperature of the heating medium supplied increases from low to high, the control step of the turbine includes: 1) starting the high-pressure turbine;

2) Compare the difference between the detection value of the heating medium supply temperature detector and the detection value of the heating medium discharge temperature detector △Th and the temperature difference threshold Sth, if △Th<=Sth, go to step 21; if △Th> Sth, go to step 22;

21) Compare the generator output power W1 and Sp1 in the first power generation cycle, where Sp1 is the optimal power threshold corresponding to the high-pressure turbine in the first power generation cycle, if W1>=Sp1, go to step 2); if W1<Sp1, go to step 211);

211) Turn off the high-pressure turbine of the first power generation cycle, start the medium-pressure turbine of the first power generation cycle, and enter step 212);

212) Comparing the difference ΔTh between the detection value of the heating medium supply temperature detector and the detection value of the heating medium discharge temperature detector and the temperature difference threshold Sth, when ΔTh>Sth, enter step 213);

213) start the second power generation cycle, enter step 214);

214) Comparing the difference between the detection value of the heating medium supply temperature detector and the detection value of the heating medium discharge temperature detector △Th and the temperature difference threshold Sth, when △Th>Sth, enter step 215);

215) activating the high pressure turbine of the first power generation cycle;

22) start the medium pressure turbine, enter step 221);

221) Comparing the difference between the detection value of the heating medium supply temperature detector and the detection value of the heating medium discharge temperature detector △Th and the temperature difference threshold Sth, when △Th>Sth, enter step 222);

222) Start the second power generation cycle.

Preferably, when the turbines of the first power generation cycle and the second power generation cycle are both started, and the temperature of the heating medium supplied decreases from high to low, the control step includes:

a) Compare the sum W1+W2 and Sp1+Sp2+Sp3 of the generator output power W1 in the first power generation cycle and the generator output power W2 in the second power generation cycle, where Sp2 is the optimized power corresponding to the medium-pressure turbine in the first power generation cycle Threshold, Sp3 is the optimized power threshold corresponding to the high-pressure turbine in the second power generation cycle; if W1+W2<Sp1+Sp2+Sp3, then enter step b);

b) Turn off the medium pressure turbine and proceed to step c);

c) Compare the size of W1+W2 and Sp1+Sp3, if W1+W2<Sp1+Sp3, go to step d);

d) Turn off the high-pressure turbine of the first power generation cycle and turn on the medium-pressure turbine; go to step e)

e) Compare the size of W1+W2 and Sp1, if W1+W2<=Sp2, go to step f); if Sp2<W1+W2<Sp1; go to step h;

f) closing the second power generation cycle;

h) Turn off the second power generation cycle and the medium pressure turbine and switch on the high pressure turbine of the first power generation cycle.

Description of drawings

Fig. 1 is a schematic structural diagram of a power generation system according to an embodiment of the present invention.

Fig. 2 is a partial control flowchart of the power generation system of the embodiment of the present invention.

Fig. 3 is another part of the control flowchart of the power generation system of the embodiment of the present invention.

detailed description

The following embodiments of the present invention, which are disclosed herein together with their advantages and features, will become apparent by reference to the following description and accompanying drawings. Furthermore, it should be understood that the features of the various embodiments described herein are not mutually exclusive and can exist in various combinations and permutations.

Referring to Fig. 1, the power generation system of the embodiment of the present invention includes a first power generation cycle 1a, a second power generation cycle 1b, an evaporator 2, a condenser 4, a heating medium supply pipeline 10, a heating medium discharge pipeline 11, and a cooling medium supply pipeline 14. The cooling medium output pipeline 15 and the control device 9 . The first power generation cycle 1 a and the second power generation cycle 1 b respectively include a high-pressure turbine 3 , a generator 7 and a power detector 8 .

The heating medium (such as water vapor, etc.) from the medium and low temperature heat source is transported from the heating medium supply pipeline 10 to the evaporator 2 through the heating medium supply pipeline, thereby heating the working medium of the evaporator 2 (such as n-butane, iso Butane, ammonia, etc.), the working medium is used to drive the turbines of the first power generation cycle 1a and the second power generation cycle 1b to drive the generators 7 of the first power generation cycle 1a and the second power generation cycle 1b to generate electricity. The heating medium output from the evaporator 2 is discharged through the heating medium discharge pipe 11 .

Cooling Medium Supply Pipeline The cooling medium supply pipeline 14 delivers the cooling medium (such as cooling water) to the condenser 4 for cooling the working medium discharged from the turbines of the first power generation cycle 1a and the second power generation cycle 1b. The cooling medium output from the condenser 4 is discharged through the cooling medium discharge line 15 .

The working medium outlet of the evaporator 2 is divided into two paths, one of which communicates with the first power generation cycle 1 a through the first channel 12 , and the other communicates with the second power generation cycle 1 b through the second channel 13 . A flow valve 16 is arranged on the second passage 13, and the control device 9 can control whether the second passage 13 is opened or closed through the flow valve 16, thereby controlling whether to start the second power generation cycle 1b. The inlet and outlet of the heating medium of the evaporator 2 are provided with a heating medium supply temperature detector and a heating medium discharge temperature detector.

Therein, the first power generation cycle 1 a is also provided with a medium-pressure turbine 31 . The high-pressure turbine 3 and the medium-pressure turbine 31 are coupled to the generator 7 through rotating shafts, so as to drive the generator 7 to generate electricity. The first power generation cycle 1a is set such that the pipeline from the evaporator 2 into the first power generation cycle 1a is divided into two paths, one of which communicates with the working medium inlet of the high-pressure turbine 3 through the first valve 21, and the other through the second valve 22. The working medium inlet of the medium-pressure turbine 31 is connected; the working medium outlet pipeline of the high-pressure turbine 3 is divided into two paths, one of which communicates with the working medium inlet of the medium-pressure turbine 31 through the third valve 23, and the other through the fourth valve 24. The inlet of the condenser 4 communicates; the working medium outlet of the medium-pressure turbine 31 communicates with the inlet of the condenser 24 .

The control device 9 can control the working state of the steam turbine in the first power generation cycle 1 a by controlling the opening and closing of the first valve 21 , the second valve 22 , the third valve 23 and the fourth valve 24 . Wherein, the first valve 21, the second valve 22 and the fourth valve 24 are opened, and when the third valve 23 is closed, the high-pressure turbine 3 and the medium-pressure turbine 31 both use the steam output from the evaporator 2 and have the maximum rated output power; When the first valve 21 and the third valve 23 are opened, and the second valve 22 and the fourth valve 24 are closed, the rated output power is reduced; the first valve 21 and the fourth valve 24 are opened, and the second valve 22 and the third valve 23 are closed When the rated output power is further reduced; when the first valve 21, the third valve 23, and the fourth valve 24 are closed, and the second valve 22 is opened, the rated output power is the lowest.

The exhaust gas outlet of the high-pressure turbine 3 of the second power generation cycle 1 b communicates with the condenser 4 . The control device 8 controls the first valve 21, the second valve 22, the third valve 23, the fourth valve 24 and the flow valve 16 according to the power detector, the temperature detector and the working status of the first power generation cycle and the second power generation cycle. switch.

When the power generation system of this embodiment is in no-load, according to the measurement of the temperature detector, when it is judged that the temperature of the heating medium supplied increases from low to high, the control device 9 controls the first valve 21, the second valve 22, the third valve 23, The fourth valve 24 and the flow valve 16 sequentially activate the high-pressure turbine 3 of the first power generation cycle 1a, the medium-pressure turbine 31 of the first power generation cycle and the high-pressure turbine 3 of the second power generation cycle.

When the power generation system of this embodiment is at full load and all turbines are in operation, according to the measurement of the temperature detector, it is judged that when the temperature of the heating medium supplied is from high to low, the control device 9 controls the first valve 21 and the second valve 22 , the third valve 23, the fourth valve 24 and the flow valve 16, sequentially close the medium-pressure turbine 31 of the first power generation cycle 1a, and the high-pressure turbine 3 of the second power generation cycle; then, start the medium-pressure turbine 31 of the first power generation cycle, The high pressure turbine 3 of the first power generation cycle is switched off.

Through the above-mentioned embodiments of the present invention, on the one hand, the first power generation cycle 1a and the second power generation cycle 1b share the heating medium and cooling medium pipelines, and share the evaporator and condenser, thereby saving costs; on the other hand, by The setting of the medium-pressure turbine and the corresponding control valve in the first power generation cycle 1a, when the heat source heat of the medium and low temperature heat source changes greatly, the working power of the power generation system is adjusted preferentially through the switch of the turbine in the first power generation cycle 1a, thereby reducing The switch requirement for the second power generation cycle 1b is reduced, the adaptability of the system is improved, and the adjustable power range is increased.

The partial control method of the power generation system in the embodiment of the present invention, as shown in Figure 2 (wherein the turbine that is not indicated to be started means that it is in a closed state), when the temperature of the heating medium supplied increases from low to high, the control steps of the turbine include: 1) start the high pressure turbine;

2) Compare the difference between the detection value of the heating medium supply temperature detector and the detection value of the heating medium discharge temperature detector △Th and the temperature difference threshold Sth, if △Th<=Sth, go to step 21; if △Th> Sth, go to step 22;

21) Compare the generator output power W1 and Sp1 in the first power generation cycle, where Sp1 is the optimal power threshold corresponding to the high-pressure turbine in the first power generation cycle, if W1>=Sp1, go to step 2); if W1<Sp1, go to step 211);

211) Turn off the high-pressure turbine of the first power generation cycle, start the medium-pressure turbine of the first power generation cycle, and enter step 212);

212) Comparing the difference ΔTh between the detection value of the heating medium supply temperature detector and the detection value of the heating medium discharge temperature detector and the temperature difference threshold Sth, when ΔTh>Sth, enter step 213);

213) start the second power generation cycle, enter step 214);

214) Comparing the difference between the detection value of the heating medium supply temperature detector and the detection value of the heating medium discharge temperature detector △Th and the temperature difference threshold Sth, when △Th>Sth, enter step 215);

215) activating the high pressure turbine of the first power generation cycle;

22) start the medium pressure turbine, enter step 221);

221) Comparing the difference between the detection value of the heating medium supply temperature detector and the detection value of the heating medium discharge temperature detector △Th and the temperature difference threshold Sth, when △Th>Sth, enter step 222);

222) Start the second power generation cycle.

Another part of the control method of the power generation system according to the embodiment of the present invention is shown in Figure 3 (in which the turbines that are not indicated are in the off state), when the turbines of the first power generation cycle and the second power generation cycle are both started, and the supply When the temperature of the heating medium decreases from high to low, the control steps include:

a) Compare the sum W1+W2 and Sp1+Sp2+Sp3 of the generator output power W1 in the first power generation cycle and the generator output power W2 in the second power generation cycle, where Sp2 is the optimized power corresponding to the medium-pressure turbine in the first power generation cycle Threshold, Sp3 is the optimized power threshold corresponding to the high-pressure turbine in the second power generation cycle; if W1+W2<Sp1+Sp2+Sp3, then enter step b);

b) Turn off the medium pressure turbine and proceed to step c);

c) Compare the size of W1+W2 and Sp1+Sp3, if W1+W2<Sp1+Sp3, go to step d);

d) Turn off the high-pressure turbine of the first power generation cycle and turn on the medium-pressure turbine; go to step e)

e) Compare the size of W1+W2 and Sp1, if W1+W2<=Sp2, go to step f); if Sp2<W1+W2<Sp1; go to step h;

f) closing the second power generation cycle;

h) Turn off the second power generation cycle and the medium pressure turbine and switch on the high pressure turbine of the first power generation cycle.

In addition, those skilled in the art can also make other changes within the spirit of the present invention, as long as they do not deviate from the technical effect of the present invention. These changes made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims (1)

1. a kind of electricity generation system, including the first power generation cycle, the second power generation cycle, heating medium pipeline, cooling medium pipeline with And control device：First power generation cycle, the second power generation cycle share evaporator and condenser, and it sets detection each spontaneous respectively The power detector of the generated energy of motor, the entrance and exit of the heating medium of evaporator set the supplying temperature detection of heating medium Device and heating medium discharge temperature detector；The working medium exit port of evaporator is divided into two-way, wherein passing through first passage all the way Connect with the first power generation cycle, connected all the way by second channel with the second power generation cycle in addition；Control device is examined according to electric power Device, temperature detector and the working condition of the first power generation cycle and the second power generation cycle are surveyed, is controlled high in the first power generation cycle Press at least one startup in turbine and middle-pressure turbine, and control the pressure turbine of the second power generation cycle start or Person closes；When the temperature of supply heating medium increases from low to high, the control device starts first power generation cycle successively Pressure turbine, the middle-pressure turbine of first power generation cycle and the pressure turbine of second power generation cycle；When From high to low, the control device closes the middle-pressure turbine of the first power generation cycle, second to the temperature of supply heating medium successively The pressure turbine of power generation cycle；Then, start the middle-pressure turbine of the first power generation cycle, close the high pressure of the first power generation cycle Turbine.